Module:Formatnum

-- This module is intended to replace the functionality of Template:Formatnum and related templates. local p = {}

function p.main(frame)

   local args = frame:getParent().args
   local prec    = args.prec or 
   local sep     = args.sep or 
   local number  = args[1] or args.number or 
   local lang    = args[2] or args.lang or 
   -- validate the language parameter within MediaWiki's caller frame
   if lang == "arabic-indic" then -- only for back-compatibility ("arabic-indic" is not a SupportedLanguage)
       lang = "fa" -- better support than "ks"
   elseif lang ==  or not mw.language.isSupportedLanguage(lang) then
       -- Note that 'SupportedLanguages' are not necessarily 'BuiltinValidCodes', and so they are not necessarily
       -- 'KnownLanguages' (with a language name defined at least in the default localisation of the local wiki).
       -- But they all are ValidLanguageCodes (suitable as Wiki subpages or identifiers: no slash, colon, HTML tags, or entities)
       -- In addition, they do not contain any capital letter in order to be unique in page titles (restriction inexistant in BCP47),
       -- but they may violate the standard format of BCP47 language tags for specific needs in MediaWiki.
       -- Empty/unspecified and unsupported languages are treated here in Commons using the user's language,
       -- instead of the local 'ContentLanguage' of the Wiki.
       lang = frame:callParserFunction( "int", "lang" ) -- get user's chosen language
   end
   return p.formatNum(number, lang, prec, sep ~= )

end

local digit = { -- substitution of decimal digits for languages not supported by mw.language:formatNum() in core Lua libraries for MediaWiki

   ["ml-old"] = { '൦', '൧', '൨', '൩', '൪', '൫', '൬', '൭', '൮', '൯' },
   ["mn"]     = { '᠐', '᠑', '᠒', '᠓', '᠔', '᠕', '᠖', '᠗', '᠘', '᠙'},
   ["ta"]     = { '௦', '௧', '௨', '௩', '௪', '௫', '௬', '௭', '௮', '௯'},
   ["te"]     = { '౦', '౧', '౨', '౩', '౪', '౫', '౬', '౭', '౮', '౯'},
   ["th"]     = { '๐', '๑', '๒', '๓', '๔', '๕', '๖', '๗', '๘', '๙'}

}

function p.formatNum(number, lang, prec, compact)

   -- Do not alter the specified value when it is not a valid number, return it as is
   local value = tonumber(number)
   if value == nil then
       return number
   end
   -- Basic ASCII-only formatting (without paddings)
   number = tostring(value)

   -- Check the presence of an exponent (incorrectly managed in mw.language:FormatNum() and even forgotten due to an internal bug, e.g. in Hindi)
   local exponent
   local pos = string.find(number, '[Ee]')
   if pos ~= nil then
       exponent = string.sub(number, pos + 1, string.len(number))
       number = string.sub(number, 1, pos - 1)
   else
       exponent = 
   end

   -- Check the minimum precision requested
   prec = tonumber(prec) -- nil if not specified as a true number
   if prec ~= nil then
       prec = math.floor(prec)
       if prec < 0 then
           prec = nil -- discard an incorrect precision (not a positive integer)
       elseif prec > 14 then
           prec = 14 -- maximum precision supported by tostring(number)
       end
   end

   -- Preprocess the minimum precision in the ASCII string
   local dot
   if (prec or 0) > 0 then
       pos = string.find(number, '.', 1, true) -- plain search, no regexp
       if pos ~= nil then
           prec = pos + prec - string.len(number) -- effective number of trailing decimals to add or remove
           dot =  -- already present
       else
           dot = '.' -- must be added
       end
   else
       dot =  -- don't add dot
       prec = 0 -- don't alter the precision
   end

   if lang ~= nil and mw.language.isKnownLanguageTag(lang) == true then
       -- Convert number to localized digits, decimal separator, and group separators
       local language = mw.getLanguage(lang)
       if compact then
           number = language:formatNum(tonumber(number), { noCommafy = 'y' }) -- caveat: can load localized resources for up to 20 languages
       else
           number = language:formatNum(tonumber(number)) -- caveat: can load localized resources for up to 20 languages
       end
       -- Postprocessing the precision
       if prec > 0 then
           local zero = language:formatNum(0)
           number = number .. dot .. mw.ustring.rep(zero, prec)
       elseif prec < 0 then
           -- TODO: rounding of last decimal; here only truncate decimals in excess
           number = mw.ustring.sub(number, 1, mw.ustring.len(number) + prec)
       end

       -- Append the localized base-10 exponent without grouping separators (there's no reliable way to detect a localized leading symbol 'E')
       if exponent ~=  then
           number = number .. 'E' .. language:formatNum(tonumber(exponent),{noCommafy=true})
       end
   else -- not localized, ASCII only
       -- Postprocessing the precision
       if prec > 0 then
           number = number .. dot .. mw.string.rep('0', prec)
       elseif prec < 0 then
           -- TODO: rounding of last decimal; here only truncate decimals in excess
           number = mw.string.sub(number, 1, mw.string.len(number) + prec)
       end

       -- Append the base-10 exponent
       if exponent ~=  then
           number = number .. 'E' .. exponent
       end
   end

   -- Special cases for substitution of ASCII digits (missing support in Lua core libraries for some languages)
   if digit[lang] then
       for i, v in ipairs(digit[lang]) do
           number = mw.ustring.gsub(number, tostring(i - 1), v)
       end
   end

   return number

end

return p